The 64th JSAP Spring Meeting, 2017

Presentation information

Symposium (Oral)

Symposium » Recent GFIS microscopy technology and its future prospects for R & D of materials and devices

[16p-315-1~11] Recent GFIS microscopy technology and its future prospects for R & D of materials and devices

Thu. Mar 16, 2017 1:15 PM - 6:00 PM 315 (315)

Hiroshi Mizuta(JAIST), Shinichi Ogawa(AIST)

5:45 PM - 6:00 PM

[16p-315-11] Interaction of gas field ionized nitrogen with silicon

〇(P)Marek Edward Schmidt1, Xiaobin Zhang1, Yoshifumi Oshima1, Le The Anh1, Anto Yasaka2, Teruhisa Kanzaki1, Manoharan Muruganathan1, Masashi Akabori1, Tatsuya Shimoda1, Hiroshi Mizuta1 (1.JAIST, 2.Hitachi High-Tech Science Corp.)

Keywords:Nitrogen, Molecular Dynamics

A larger number of gas molecules (among them hydrogen, helium, nitrogen and neon) can be ionized by the gas field ion source (GFIS) and used as projectiles in focused ion beam (FIB) systems. Among them, the nitrogen stands out as it forms a very strong covalent bond. It is not yet fully understood how this N2 molecule behaves during gas field ionization and sample interaction, i.e. if the bond is broken during ionization. The mass spectrum of electron ionized N2 gas shows a small amount of N+ and a larger amount of N2+. Here, we report scanning transmission electron microscopy (STEM) analysis of cross sections extracted from silicon bombarded with gas field ionized N2 molecules with a line dose from 0.24 and 9.5x103 ion/nm. The extracted implantation depths for ion energies of 25 and 16 keV are compared with theoretical values and suggest that the bond sustains the field ionization and is broken during sample interaction. We use first principle molecular dynamics simulation to support this finding (Figure 1b), in particular that the covalent bond is broken within the first few atomic layers of the impinged silicon target.